Rotatable socket for a dental handpiece

Abstract

A rotatable socket for supporting a tool for rotation in a head housing of a dental handpiece. The socket includes a cylindrical or hollow tubular shaft for supporting a tool extending out of one end and having a dog for engaging a flattened surface on the shank of the tool for transmitting torque. To hold the tool in the socket, the socket has a catch device comprising at least one resilient element with a catch nose being disposed in the interior of the shaft to extend parallel to the axis of the shaft with the catch nose releasably engaging an annular groove in the shank of the tool. To disengage the tool, the catch device also includes a pressure element, which is disposed on the housing adjacent the free end of each resilient support element and which is urged into engagement with the free end of the support element to cause disengagement of each of the catch noses when a purchase has been actuated by pressure from the operator's thumb.

I claim: 
     
       1. In a rotatable socket for supporting a tool for rotation in a head housing of a dental hand piece, said socket including a hollow cylindrical shaft having a bore for receiving a tool from one end and having a dog for engagement with a flattened surface on a shank of the tool for transmission of torque therebetween, said socket having a catch means comprising of at least one support element extending parallel to the axis of said hollow cylindrical shaft and having a catch nose extending radially inward for engagement in an annular groove in the shank of the tool disposed in said hollow cylindrical shaft, said catch means including means biasing said catch nose radially inward, said catch means including a thumb actuated purchase disposed on the head housing for releasing each of the catch noses upon actuation to allow disengagement of the tool from said socket, the improvements comprising the hollow cylindrical shaft containing an inner recess adjacent said bore for accepting the catch means, said recess receiving each support element and providing space adjacent the catch nose to enable radial outward movement of the catch nose to a position to enable disengagement of the catch nose from the tool, each support element being disposed in said recess with a free end being adjacent the other end of the shaft and a pressure element being disposed adjacent said other end of the shaft and in alignment with and disengaged from each free end, said purchase being mounted on the housing free of contact with all rotatable parts and adjacent the pressure element for relative movement so that when actuated the purchase urges the pressure element into engagement with each free end of the support element to urge each of the catch noses radially outward to a position to release a tool in said socket. 
     
     
       2. In a rotatable socket according to claim 1, wherein the pressure element comprises a resilient part having a centrally disposed portion for engaging each free end of the support element. 
     
     
       3. In a rotatable socket according to claim 2, wherein the resilient part has a plurality of support arms extending radially therefrom in a star-like manner, said support arms supporting said part on a surface of the housing with the centrally disposed part aligned coaxially with the hollow cylindrical shaft. 
     
     
       4. In a rotatable socket according to claim 3, wherein one of the support arms of the resilient part extends between the housing and a portion of the purchase to form a pivot point in which the purchase pivots during actuation. 
     
     
       5. In a rotatable socket according to claim 4, wherein the housing has a neck portion for connecting the housing to the rest of the dental handpiece, and said abutment is disposed on the head housing at a position lying opposite to the neck portion. 
     
     
       6. In a rotatable socket according to claim 1, wherein said inner recess has a first portion and a second portion, said first portion being concentric with the bore and having a radius larger than the radius of the bore by an amount corresponding to the thickness of the support element to enable receiving the support element with the free end extending into the second portion, said second portion having dimensions to enable the radial outward displacement of the free end to disengage the catch nose from the shank, said second portion receiving the dog for engagement with the flattened surface of the shank of the tool when inserted in the cylindrical shaft, said dog coacting to secure the support element in said first portion. 
     
     
       7. In a rotatable socket according to claim 6, wherein said support element comprises a ring portion inserted in the first portion and has at least one resilient arm supporting a catch nose extending axially therefrom into the second portion of the inner recess. 
     
     
       8. In a rotatable socket according to claim 7, wherein the support element has a single arm. 
     
     
       9. In a rotatable socket according to claim 7, wherein the support element has a pair of arms diametrically opposite to one another. 
     
     
       10. In a rotatable socket according to claim 6, wherein the second portion of the inner recess is disposed in an area adjacent the upper bearing supporting the hollow cylindrical shaft in said head housing, said upper bearing being opposite said one end. 
     
     
       11. In a rotatable socket according to claim 6, wherein the dog is disposed on an annular member which is firmly inserted in the second portion of said inner recess. 
     
     
       12. In a rotatable socket according to claim 11, wherein the support element comprises a sleeve-shaped member having a base part with at least one resilient tongue extending therefrom and parallel to the axis of said sleeve shaped member, said base part being inserted into the first portion of the inner recess with each resilient tongue extending into the second portion so that the catch nose disposed on each of the resilient tongues is positioned in the second portion of the recess. 
     
     
       13. In a rotatable socket according to claim 12, wherein the head housing has a neck part for connecting the head housing to the rest to the dental handpiece, said purchase being disposed on the head housing to rest against an abutment on an upper end of the head housing lying opposite to the neck part. 
     
     
       14. In a rotatable socket according to claim 1, wherein the head housing has a neck part for connecting the head housing to the rest of the dental handpiece, said purchase being disposed in the head housing to rest against an abutment on an upper end of the head housing lying opposite to the neck part. 
     
     
       15. In a rotatable socket according to claim 14, wherein the abutment is formed by a rigid bearing axle mounting the purchase for pivotable movement.